Method of constructing metal bellows



'fi v n? 41. CONKLIN METHOD OF CONSTRUCTING METAL BELLOWS Original Filed Sept. 27, 1935 UT/Z/ZAT/O/V CIRCUIT 3 It is OSCILLATOR INVENTOR J.W.CONKLlN BY 7% q ATTORN EY atented May 27, 1941 METHOD OF CONSTBUCTING METAL BELLOWS James W. Conklin, Audubon, N. -J., assignor to Radio Corporationoi America, a corporation of Delaware Original application September 27, 1935, Serial No. 42,410. Divided and this application August 27, 1938, Serial No. 227,140

4 Claims.

This invention is a division of my copending application Serial No. 42,410, filed September 27, 1935, and relates to a metal bellows and to a method of constructing odd sized bellows for special purposes,

Metal bellows are used in a wide variety of industrial and domestic applications, as, for example, in arrangements employing pressure controlled motion, also as thermostatically actuated devices, expansion joints, seals, etc. In commercial manufacture,' the bellows are formed from drawn or punched seamless tubings by rolling, spinning, and by hydraulically forcing into dies. To make a bellows of any specific diameter, flexibility, and length, it is necessary to have seamless tubing or the means for making it and special collapsible dies and tools for forming it. One disadvantage with previous methods or production is that the construction of a few units to odd specifications is very costly. Another difficulty lies in the fact that commercial methods are not well adapted to making very thin walled that metal bellows ments showing the use of metal bellows in temperature compensation systems are described in United States Patents Nos. 2,103,515, granted December 28, 1937, to Conklin et al.; 2,108,895, granted February 22, 1938, to Kroger; and 2,124,029, granted July 19, 1938, to Conklin et al. In these patents, it is usually desirable or neces-' sary that the bellows be of a specific odd-size outside diameter, and it is further desirable that they have a very high-flexibility so as to present minimum static opposition to longitudinal motion. These requirements, it has been found. can very seldom be met exactly by commercially available bellows, and as stated before, the cost of producing special bellows by commercial methods is prohibitive.

In the past, special bellows have sometimes been formed by soldering or rolling together flat or die formed plates. These bellows, while considerably simpler to make than the commercial variety, still present difficulties, particularly in assembling. However, this type of bellows is not suitable for use with electrical conductors of the kind hereinabove described since they present sharp outside edges which are not suitable for use as capacity cylinders,

One of the objects of the present invention is to provide a form of metal bellows which can easily be made to have any specific dimensions and degree of flexibility without the use of specialized tools and machines.

A further object is to provide a simple process for constructing a type of metal bellows which can be used as a capacity cylinder in an electrical system.

In the bellows of the. present invention, each section is formed of a pair of annular discs having overlapping folds on their inner and outer edges, the individual discs being joined at their overlapping edges; As each disc is formed directly from flat sheet material, any weight of material may be used and any desired degree of flexibility obtained.

An advantage of the invention is the fact that the only machine required in the construction of these bellows is a lathe having sufllcient swing to accommodate the outside diameter of the bellows. By swing," of course, is meant the radius of free movement of the lathe, i. e., the radial distance from the lathe spindle axis to the ways as a measure of the largest piece which can be rotated in the lathe.

The details of the bellows and its method of construction will be better understood .by referring to the accompanying drawing wherein:

Fig. 1 illustrates a flat metallic plate before being changed to form a disc of the bellows of the invention;

Fig. 1a illustrates in perspective and in section, for the sake of clarity,only one half of a disc made from the plate of Fig. 1;

Fig. 1b illustrates in perspective unit of a complete bellows, in accordance with the invention, comprising two overlapping discs;

Fig. 1c shows an elevation view, and Fig. 1d anend view of a bellows made of several sections, of the type shown in Fig. lb;

Figs, 2a. and 3a illustrate, respectively, elevation views, and Figs. 2b and 3b end views of two different methods of making the discs of the circuit.

Fig. 1 shows a flat metallic plate with an open a section or.

center from which the disc of the desired form for use in the bellows of the invention is made. The blank plates ofthe type shown in Fig. 1 are cut from sheet metal by any available means and may be directly out to a finished diameter or rough cut slightly over-size and finished after forming by cutting OK with a suitable tool.

Fig. la shows the form of the disc made from the plate of Fig. l, by the method of the invention hereinafter described in connection with Figs. 2 and 3. Only one-half of the disc has been shown in order to more clearly emphasize the salient features of the disc, it being understood, of course, that the other half of the disc is identical with that illustrated.

Fig. lb illustrates the manner in which two similar discs at and b, of the type shown in Fig. la, except for slight, differences in their dimensions, telescope one another to form a section or unit of the bellows of the invention. Similar units or sections of this kind may be arranged to telescope each other to build up a complete bellows of a plurality of sections, as shown in elevation in Fig. 10. Each section comprises a pair of discs :1 and b, the disc a having its inside and outside diameter greater than disc b by the thickness of the metal. These discs are Joined at their overlapping seams, as at c, in a suitable manner, such as by soldering, brazing, or welding, depending upon the thickness of the metal and the strength of the joint required. In this manner there is obtained a bellows which is electrically continuous in form and which can be used as a capacity cylinder in an electrical resonator of the type described in the above mentioned applications, supra, and shown in Fig. 4. Referring to Figs. 2a and 2b, which illustrate one method of forming the paired discs and b of each section of the bellows, there is shown a ring R which is adapted to be held in a chuck or fastened to the face plate P of a lathe, and a clamping ringR' fastened to ring R, either by several screws S as shown, or by several small clumps of the type shown in Figs. 3a and 3b.

In the process of making the discs for the bellows of the invention, two of the blank plates shown in Fig. l are clamped .together between the forming plates R and R, with the edges of the plates projecting as indicated by the dotted lines in Fig. 2a. Now with the lathe revolving, the edges are spun over as indicated, from the position shown in dotted lines to that shown in solid lines. The spinning operation is very simple and consists merely in forcing over the metal edges projecting beyond the clamping means R, R with a suitable tool, usually of fibre or hardwood, used against a rest or suitable fulcrum. It will be apparent that the simultaneous spinning of two blanks together, which first have the form shown in dotted lines in Fig. 2a, results automatically in the paired discs (1 and b of slightly different dimensions.

The method of spinning shown in Figs, 2a and 2b, wherein the screws S are employed for clamping the rings R and R together, may be used when the bellows is employed as a capacity cylinder in an electrical resonator which is not required to be air tight, in which case the holes for the clamping screws are not objectionable. However, when the bellows is required to be of the gas or liquid tight type, the clamping method of Fig. 3a should be used, wherein specially designed clamps C are mounted on the outside of the ring R when the inside edges are to beformed and on the inside of the ring R when the outside edges are to be formed.

After the discs are spun, and dressed off, they are removed from the forms of Figs. 2a and 3a and assembled as in Fig. lo, and soldered together or otherwise joined ,to form a complete bellows.

The foregoing method of spinning the two discs a and b together constitutes an important be suitable for only one thickness of metal,

whereas with the method of spinning of the invention shown in Fig. 2a and Fig. 3a, any

reasonable thickness of metal may be used with the same spinning dies to form bellows having substantially the same dimensions but of varying wall thickness and consequent flexibility.

Fig. 4 illustrates one use to which the bellows oi the invention may be applied. This figure illustrates a concentric transmission line resonator for controlling the frequency of an oscillator. This resonator comprises an inner conductor l and an outer conductor 2, the overall length of the inner conductor being maintained substantially constant by means of an Invar rod I having a low temperature coefllcient and a capacity bellows l constructed in accordance with the principles of this invention. With change in temperature it .will be seen that inner conductor I can change its length from the lowermost portion to the upper portion Joining with the bellows without cha ing the overalleffective length of the inner conductor comprising conductor I and bellows 4. This is because the bellows will coritract and expand with variations in length of the conductor I due to variations in temperature,

. while the entire overall length, as determinedby the projection of the uppermost end of the bellows l on the inner surface of the outer conductor 2 is maintained constant.

In circuit with the line resonator I, 2 of Fig. 4 is shown, by way of example only, an oscillation generator comprising an electron discharge device whose frequency is controlled by the resonator. Since this particular circuit forms no part of the present invention per se, and is adequately described in the foregoing patents, it will not be further referred to herein.

It will be understood, of course, that although the bellows and its process of construction have been described in their simplest form, various changes can be made by those skilled in the art without departing from the spirit and scope of the invention. For example, although Figs. 2a and 31: indicate two methods of clamping the blanks a and b to the lathe, in practice more refined means would be justifiable. Also, the shape of the edges of the plates a and b can be varied to suit different applications, such changes in the shape of the edges only requiring that the forming rings be varied to conform with the desired shape. The lathe'may. be used to form a square edged bellows, a shape which is suitable for use as a capacity cylinder, since the edges sure applications, since this has greater strength in resisting internal pressure.

What is claimed is:

1. The method of forming metal bellows which comprises forming a single unit by clamping together, face to face, two blank plates having open circular center portions, at points between the outer and inner edges of said plates, forcing the outer edges of said plates over the clamping means in one direction and the inner edges of said plates over the clamping means in the opposite direction, separating said plates and nesting the smaller diameter plate into the larger diameter plate at their corresponding edges.

2. The method \of forming metal bellows which comprises forming a single unit by clamping together, face to face, two blank plates having open circular center portions, at points between the outer and inner edges of said plates, forcing the outer edges of said plates over the clamping means in one direction and the inner edges of said plates over the clamping means in the opposite direction, and separating said plates and nesting the smaller diameter plate into the larger diameter plate at their corresponding edges, forming other units in the same manner,- nesting the smaller diameter plate of one unit into the larger diameter plate of an adjacent unit, and joining said units together at their overlapping edges.

' 3. The methodof forming metal bellows which comprises forming a single unit by clamping together coextensively two blank plates of the same size having open center portions, at points between the outer and inner edges of said plates, forcing the outer edges of said plates over the clamping means in one direction and the inner edges of said plates over the clamping means in the opposite direction, separating said plates and nesting the so formed smaller diameter plate into the so formed larger diameter plate at their corresponding edges.

4. The method of forming metal bellows which comprises forming a single unit by clamping together coextensively two blank plates of the same size having open center portions, at points between the outer and inner edges of said plates, forcing the outer edges of said plates over the clamping means in one direction and the inner edges of said plates over the clamping means in the opposite direction, and separating said plates and nesting the so formed smaller diameter plate into the so formed larger diameter plate at their corresponding edges, forming other units in the same manner, nesting the smaller diameter plate of one unit into the larger diameter plate of an adjacent unit, and joining said units together at their overlapping edges.

JAMES W. CONKLIN. 

